1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor and a mounting board having the multilayer ceramic capacitor mounted thereon.
2. Description of the Related Art
A multilayer ceramic capacitor, a multilayer chip electronic component, is a chip type condenser commonly mounted on printed circuit boards of various electronic products, such as image display devices including a liquid crystal display (LCD), a plasma display panel (PDP) and the like, a computer, a personal digital assistant (PDA), a mobile phone, and the like, and provided for the charging or discharging of electricity.
A multilayer ceramic capacitor (MLCC) may be used as a component in various electronic products due to having the advantages of a small size, high capacitance, and ease of mounting.
A multilayer ceramic capacitor may have a structure in which a plurality of dielectric layers and a plurality of internal electrodes having different polarities and provided between the dielectric layers, are alternately laminated with each other.
However, since these dielectric layers have piezoelectricity properties and electrostrictive properties, a piezoelectric phenomenon may occur and thus cause vibrations among the internal electrodes when AC or DC voltage is applied to the multilayer ceramic capacitor.
Such vibrations are transferred to a printed circuit board on which the multilayer ceramic capacitor is mounted, through external electrodes of the multilayer ceramic capacitor, and the entire printed circuit board becomes an acoustic reflection surface to transmit the sound of vibrations as noise.
The vibrating sound may correspond to an audible frequency range of 20 to 20000 Hz, a frequency which may cause listener discomfort and which is known as acoustic noise. Researches into the reduction of such acoustic noise are needed.
Patent Document 1 below discloses a multilayer ceramic capacitor in which a lower cover layer is thicker than an upper cover layer and internal electrodes are formed to be coplanar with respect to a substrate.